Safety razors having one or two blades permanently mounted in a disposal cartridge, or a disposable razor, have become highly popular. In most such cartridges or disposable razors which use a pair of tandomly mounted blades, the blades are separated by a spacer; and the cutting edge of the upper blade is spaced slightly rearwardly of the cutting edge of the lower blade. The position or spatial relationships between the blade or blades and the other rigid portions of the cartridge or disposable razor, are fixed. Typical constructions of this type of razor blade cartridge assembly are disclosed in the Dorion, Jr. U.S. Pat. Nos. 3,724,070 and 3,786,563; and Perry U.S. Pat. No. 3,768,162.
In the Dorion and Perry patents mentioned above, the handle of the razor and the other portions of the cartridge holding the blades, are secured together in a fixed relationship. The shaving efficiency of a safety razor using cartridges of the type disclosed in the Dorion and Perry patents, however, has been improved by mounting the blade assembly on a pivot on the razor handle; so that the assembly pivots during a shaving operation. Theoretically, this permits the blade assembly to follow the contours of the surface being shaved more closely than if the pivoting feature was not used. Typical systems of this type are disclosed in the Jacobson U.S. Pat. No. 4,621,424; Nissen U.S. Pat. No. 4,026,016; and Jacobson U.S. Pat. No. 4,551,916. These patents are typical of this type of assembly, which is also the subject matter of other prior art patents not mentioned here.
A different approach to providing increased shaving efficiency has been attempted by retaining the blade assembly as a whole, stationary, while at the same time, permitting movement of individual components, such as the guard and the blades, in response to forces encountered during shaving. Patents which disclose shaving units of this type for permitting independent movement of the blade or blades, and the guard, in response to forces which essentially are perpendicular to the plane of the blades, are Francis U.S. Pat. No. 4,168,571, in which the guard and the blades are mounted on a resilient pad, to permit movement perpendicular to the plane of the blades, as well as rocking of the blades; and Jacobson U.S. Pat. No. 4,270,268, in which the guard and two blades are independently spring-mounted within the cartridge for movement perpendicular to the plane of the blades. This same resilient mounting to produce the independent movement of the blades and guard, as disclosed in the Jacobson '268 patent, also is disclosed in the Jacobson U.S. Pat. Nos. 4,492,024; 4,498,235; and 4,573,266. In the '024 and '235 patents, the entire cartridge, additionally, is pivotally mounted on the handle in a manner similar to the pivotal mounting of the cartridge disclosed in Jacobson U.S. Pat. No. 4,621,424.
In the patents listed above, which permit independent bending movement of the blades in a plane perpendicular to the plane of the cutting edge of the blades, the space or vertical distance between the two blades (in a two-blade cartridge) is not maintained by a fixed spacer. This distance between the blades can vary in accordance with the different relative pressures applied to the blades during the shaving action. Consequently, the resiliency which is provided by the springs, to allow the blades to follow various contours in the surface of the skin being shaved, in some situations, interferes with the efficient operation of the second or rearward mounted blade at times when the spacing between the two blades is reduced. In such cases, the second blade overlies the first or leading blade by such a small amount that the two blades functionally "merge" and the "second cut" provided by the trailing or rearward blade is not effected. A similar problem exists between the guard and the lowermost blade where, in some circumstances, the vertical space between the guard and the leading or lowermost blade may be reduced to the point where efficient shaving is momentarily interrupted.
It is desirable to provide a razor blade assembly in the form of a cartridge in which blades are movable in response to forces encountered during a shaving operation, but which maintains the desired vertical spacing of the cartridge components throughout the shaving operation.